Widget links maps:// directly so CarPlay can route to Apple Maps

- The widget now uses the native maps://?daddr= scheme for taps in both
  sizes. In CarPlay there is no containing app to relay through, but since
  Apple Maps IS a CarPlay app, the system may route the tap straight to
  Maps on the car display (WWDC25: widgets can launch apps in CarPlay).
- iOS keeps working via onOpenURL: the app now forwards maps:// URLs (if
  the Home Screen delivers them to the app), plus legacy fuelboard:// and
  http://maps.apple.com links from older cached timelines.
- No public API exists for a widget to detect CarPlay context, so the
  single maps:// link serves both; the app-side forward is the iOS safety
  net. 35 tests pass.

Shared/FuelStore.swift

@@ -159,13 +159,16 @@ struct FuelStation: Identifiable, Codable, Equatable {
         URL(string: "maps://?daddr=\(lat),\(lng)&t=d")
     }
 
-    /// Widget tap URL. WidgetKit widgets can ONLY open their containing app:
-    /// the system hands this URL to FuelBoard via `onOpenURL`, which then
-    /// forwards to Apple Maps. So the widget link uses our own registered
-    /// `fuelboard://` scheme rather than `maps://` (which would arrive in the
-    /// app and be silently dropped).
+    /// Widget tap URL — the native Maps scheme (`maps://`). From the iOS Home
+    /// Screen the system may either (a) open Maps directly, or (b) deliver the
+    /// URL to the containing app, where FuelBoardApp.onOpenURL forwards it to
+    /// Maps. In CarPlay there is no containing app, but because `maps://`
+    /// targets Apple Maps — an app that IS in CarPlay — the system may route
+    /// the tap straight to the car display, bypassing the app entirely. This
+    /// is the only scheme with a chance of working in CarPlay; the old
+    /// `fuelboard://` relay is kept as a handled fallback in onOpenURL.
     var widgetDirectionsURL: URL? {
-        URL(string: "fuelboard://directions?lat=\(lat)&lng=\(lng)")
+        URL(string: "maps://?daddr=\(lat),\(lng)&t=d")
     }
 
     /// Name of the bundled brand logo asset, or nil if unknown.